Insoluble Oxalate Contents Research Articles

Total and soluble oxalate content of some Indian spices.

Spices, such as cinnamon, cloves, cardamom, garlic, ginger, cumin, coriander and turmeric are used all over the world as flavouring and colouring ingredients in Indian foods. Previous studies have shown that spices contain variable amounts of total oxalates but there are few reports of soluble oxalate contents. In this study, the total, soluble and insoluble oxalate contents of ten different spices commonly used in Indian cuisine were measured. Total oxalate content ranged from 194 (nutmeg) to 4,014 (green cardamom) mg/100g DM, while the soluble oxalate contents ranged from 41 (nutmeg) to 3,977 (green cardamom) mg/100g DM. Overall, the percentage of soluble oxalate content of the spices ranged from 4.7 to 99.1% of the total oxalate content which suggests that some spices present no risk to people liable to kidney stone formation, while other spices can supply significant amounts of soluble oxalates and therefore should be used in moderation.

Oxalate Accumulation in Forage Plants: Some Agronomic, Climatic and Genetic Aspects

Oxalic acid is synthesized by a wide range of plants. A few of them are forage plants that can cause oxalate poisoning in ruminants under certain conditions. In this paper, the role of some agronomic, climatic and genetic factors in minimizing oxalate accumulation in forage plants has been discussed. Research indicates that the content of oxalate in forage can be controlled by fertilizer application. For example, nitrate application resulted in higher contents of soluble and insoluble oxalates than ammonium application. With an increased rate of potassium application, soluble oxalate content showed an increasing trend and insoluble oxalate content showed a decreasing trend. With an increased rate of calcium application, soluble oxalate content showed a decreasing trend and insoluble oxalate content showed a reverse trend. Other agronomic factors such as growing season, harvesting practices, plant maturity, plant species, plant variety and plant parts can also have a large effect on oxalate accumulation. However, the potential benefits of the above approaches for improving forage quality have not been fully exploited. In addition, there is still insufficient information to fully utilize means (e.g. plant nutrients, season and soil moisture) to minimize oxalate accumulation in forage plants. Therefore, more research is required for a better understanding of the interactions between oxalate and the above-mentioned factors in forage plants.

Effect of Cooking on Soluble and Insoluble Oxalate Contents in Selected Pakistani Vegetables and Beans

The present study evaluated the effects of cooking on the total, soluble and insoluble oxalate contents in six different types of locally consumed vegetables and beans (spinach, carrots, beet root, white bean, red bean and soybean). The foods were cooked in water until they reached the soft consistency (12–15 min for vegetable and 2 h for beans). The raw and cooked samples were analyzed for their soluble and insoluble oxalate contents using the HPLC techniques. The total oxalate content of raw spinach, carrot, beet root, white bean, red bean and soybean, were found to be 978 ± 5, 49 ± 7, 67 ± 12, 158 ± 16, 113 ± 15, and 497 ± 22 mg/100 g of fresh weight respectively. The total oxalate contents of these foods after boiling were 477 ± 8, 16 ± 9, 52 ± 14, 47 ± 17, 72 ± 17, and 224 ± 25 mg/100 g of fresh weight respectively. The results showed that boiling significantly (P < 0.05) reduced both soluble and insoluble oxalate contents. More losses were observed in the soluble than the insoluble oxalates. The reduction in soluble oxalate in different vegetables ranged from 16 to 66% whereas in beans ranged from 40 to 77%. The data suggests that the use of boiled vegetables can be an effective strategy for reducing the dietary intake of oxalates in individuals predisposed to the development of kidney stones.

Interactive Effects of Nitrogen and Potassium Fertilization on Oxalate Content in Napiergrass (Pennisetum purpureum)

Ingestion of forage containing a large quantity of soluble oxalate can result in calcium deficiency and even death of livestock. Fertilization is one of the most practical and effective ways to improve yield and nutritional quality of forage. An experiment was conducted to determine the effects of nitrogen (N) fertilization (150, 300 and 600 kg/ha) across varying levels (150, 300 and 600 kg/ha) of potassium (K) on oxalate accumulation in napiergrass (Pennisetum purpureum). Application of N at 300 kg/ha produced higher dry matter yield than at 150 or 600 kg/ha, while K fertilization had no effect on yield. In general, N fertilization did not affect the soluble and total oxalate contents, but slightly affected the insoluble oxalate content. Soluble oxalate content showed an increasing trend and insoluble oxalate content showed a decreasing trend with increasing K level, but total oxalate content remained relatively constant. There were significant interactions between N and K fertilization for the content of soluble and insoluble oxalate fractions. The greatest increase in soluble oxalate content with N level at 300 kg/ha was found at the high level (600 kg/ha) of K application. The greatest increase in insoluble oxalate content with N level at 600 kg/ha was found at the low level (150 kg/ha) of K application. These results indicated the possibility of controlling the content of soluble and insoluble oxalate fractions in forage by fertilization.

Effects of Nitrogen and Calcium Nutrition on Oxalate Contents, Forms, and Distribution in Spinach

ABSTRACT A hydroponic experiment was conducted to study the effects of nitrogen (N) and calcium (Ca) nutrition on oxalate contents of different forms in spinach tissues. Results showed that leaves were the main locations of oxalates in spinach. Total oxalate, soluble oxalate, and insoluble oxalate contents were highest in leaves, followed by petioles and then roots. Soluble oxalate was the dominant form of oxalate in spinach. Nitrogen and Ca2+ (calcium ion) concentrations could markedly affect oxalate contents. Soluble oxalate contents in leaves increased obviously with the increase of N concentration until 8 mmol L−1, above which oxalate content started to decrease. Supplied with the same amount of N, increasing Ca2+ concentration reduced soluble oxalate content in leaves. Total oxalate reached the lowest with 5 mmol L−1 of Ca2+ supply. Leaves and petioles had lower total oxalate and lower proportion of soluble oxalate when N and Ca2+ concentrations were 8 and 5 mmol L−1.

Change of oxalate form in pot‐grown napiergrass (Pennisetum purpureum Schumach) by application of calcium hydroxide

AbstractOxalate interferes with the absorption of calcium (Ca) in livestock. However, insoluble oxalate, which presents mostly as a complex combined with Ca, is not considered to be a problem in ruminants. The objective of this study was to test the possibility of increasing insoluble oxalate content in plants by increasing Ca supply in pot‐grown napiergrass (Pennisetum purpureum Schumach). The plants were cut three times at approximately 2‐month intervals from summer to autumn. Four treatments (0, 30, 60 and 90 g m−2) of Ca(OH)2 were applied in three equal split doses: before transplanting and soon after the first two cuttings. At almost all of the cuttings, soluble oxalate in forage showed a decreasing trend and insoluble oxalate and Ca concentration showed a reverse trend with an increased rate of Ca(OH)2 application. Averaged over the three cuttings, the 90‐g Ca(OH)2 treatment was most effective in reducing soluble oxalate by increasing insoluble oxalate, with significant (P &lt; 0.05) differences between the 0‐ and 90‐g Ca(OH)2 treatments. However, total oxalate content was not affected (P &gt; 0.05) by the rate of Ca(OH)2 application. Moreover, Ca(OH)2 application did not affect dry matter yield and the concentrations of magnesium, potassium and sodium of plant material. It may be concluded that the level of soluble oxalate in plants can be partially replaced by formation of insoluble oxalate using Ca(OH)2 fertilizer.

Effect of Salinity Stress on Dry Matter Yield and Oxalate Content in Napiergrass (Pennisetum purpureum Schumach)

Sodium is involved in elevation of oxalate content in some plant species and this element is abundant in saline soils. Oxalate causes precipitation of insoluble calcium oxalate in the rumen and kidneys. The intention of this study was to evaluate the effect of soil salinity stress on dry matter yield and oxalate content in pot-grown napiergrass (Pennisetum purpureum Schumach). Plants were cut three times at 56, 118 and 179 d after transplanting to the pots. Five salinity treatments were used containing various concentrations of NaCl solution as follows: 0, 100, 300, 600 and 900 mM. At 28, 42, 84, 98, 146 and 160 d after transplanting, plants were irrigated with one liter of the particular treatment for each application. Dry matter yield of napiergrass was not affected (p>0.05) by salinity treatments. Plants treated with 100 mM NaCl exhibited a higher soluble oxalate content compared to other treatments, but the differences were not statistically significant (p>0.05). Although salinity treatments had significant (p<0.05) effects on insoluble and total oxalate contents in plant tissue between the 100 and 900 mM NaCl treatments, the differences were too small to be considered biologically important. The present study indicates that where the soil is high in NaCl, napiergrass will tend to grow well and be low in oxalate. (Key Words : Napiergrass, Salinity, Sodium Chloride, Soluble Oxalate, Total Oxalate)

Effects of levels of nitrogen fertilizer on oxalate and some mineral contents in napiergrass (Pennisetum purpureum Schumach)

AbstractIn a number of plant species, nitrogen fertilization leads to a higher oxalate content of the plant. Various tropical grasses sometimes contain oxalate in sufficient concentrations to induce calcium deficiency in grazing animals. The present study was undertaken to investigate the effect of increasing level of N (0, 10, 30, 60 and 90 g N m−2 using urea) on oxalate and some mineral contents in napiergrass (cv. dwarf‐late). We found that the total dry matter yield increased significantly (P &lt; 0.001) with increasing N up to 30 g N m−2 applied, but no significant difference was observed among the N levels of 30, 60 and 90 g m−2. The oxalate content was not increased with increased levels of N fertilization in all cut forages, except for insoluble oxalate content at third‐cut forage which increased significantly (P &lt; 0.05) with increased level of N fertilizer. The content of soluble oxalate in plants was positively correlated (r2 = 0.76, P &lt; 0.001) with potassium concentration, while the content of insoluble oxalate was positively correlated with calcium (r2 = 0.69, P &lt; 0.001) and magnesium (r2 = 0.65, P &lt; 0.001) concentrations. The study suggests that while applying N fertilizer as urea during cultivation of napiergrass, oxalate accumulation may not be a matter of concern.

Calcium oxalate crystals of some Crataegus (Rosaceae) species growing in Aegean region

In this study, Ca oxalate crystals were isolated from the leaves and X-ray diffraction identified them as weddelite in Crataegus pontica C. Koch, C. stevenii Polar., C. monogyna ssp. monogyna Jacq. in C. orientalis var. orientalis Pallas ex Bieb. both whewellite and weddelite crystals were found. Although there were some differences among the soluble and insoluble oxalate contents, they were not notable in the species of C. stevenii (10%; 18%), C. orientalis (12.4%; 15%), C. monogyna (12.9%; 13%), whereas in C. pontica the difference was so great with the lowest soluble (4%), and highest (28%) insoluble oxalate content. Crystals have tetragonal or prismatic shape in general but tetrahedral kinked and straight shapes were seen in C. orientalis, tetragonal aggregates in C. stevenii, and also pseudo-tetrahedral cordate (heart) shape were found in C. monogyna ssp. monogyna and C. pontica. As the crystal biomineralization is under genetic control, this characteristic hydration state of crystals of Crataegus orientalis var. orientalis must be important for systematic phylogenetics.

The effect of soaking and cooking on the oxalate content of taro leaves

Pacific Island people commonly eat taro (Colocasia esculenta var. Schott) as a staple food in their home islands and also like to consume this familiar food when living in New Zealand. Some of these foods are imported from the islands and some attempts are, currently, being made to grow these crops in New Zealand. The taro leaves in this experiment were grown in a greenhouse in the North Island of New Zealand. The soluble oxalate content of the raw leaves was 236.10 mg oxalate/100 g wet matter (WM). Soaking the raw leaves in water for 30 min marginally reduces the soluble oxalate content by leaching into the tap water. Soaking for 18 h results in a 26% reduction in the soluble oxalate content of the raw leaves. During the soaking treatments the insoluble oxalate (calcium oxalate) content of the leaves remained constant (mean 171.64 mg oxalate/100 g WM).Boiling the taro leaves resulted in a 36% loss of soluble oxalates, while the soluble oxalate content of baked tissue was very similar to the raw tissue. The mean insoluble oxalate content of the raw, boiled and baked tissue was 226.28 mg oxalate/100 g WM. Overall, boiling the taro leaves was an effective way of reducing the soluble oxalate content of the cooked tissue.

Effect of Cooking on the Soluble and Insoluble Oxalate Content of Some New Zealand Foods

Oxalates occur as end products of metabolism in a number of plant tissues; some leafy plants and some root crops contain markedly high levels of soluble and insoluble oxalates. When consumed these oxalates can bind calcium and other minerals. Measurement of oxalate content in vegetables commonly consumed in New Zealand shows that cooking reduces the oxalate content of the food by leaching losses into the cooking water. Roots and brassicas grown in New Zealand appear to contain relatively low levels of oxalates. Leafy vegetables such as silverbeet and NZ spinach appear to approach and exceed levels found in rhubarb stalks, although New Zealand silverbeet stems contain lower levels.

Determination of Soluble and Insoluble Oxalate Contents in Kiwifruit (Actinidia deliciosa) and Related Species.

Change of oxalate contents in green-fleshed 'Hayward' and 'Bruno' and in yellow-fleshed 'Golden King' and 'Yellow Queen' kiwifruit, and related species were analyzed during their development and storage. Calcium oxalate crystals in kiwifruit are observed in the form of raphide showing long and needle-shape in the green-fleshed cultivars but short in the yellow-fleshed ones ; the raphide crystals in A. arguta and A. rufa were likewise short. The oxalate contents, which was determined by enzymatic analysis, attained maximum in fruit sampled in July during their early development period. The level gradually decreased with the increase in size until harvest in late October ; it continued to decrease during cold storage. The oxalate content decreased slightly faster in the yellow-fleshed fruits than it did in the green-fleshed ones. The oxalate content in A. arguta was lower than that in A. deliciosa, whereas that in A. rufa was slightly higher.

Effect of nitrogen on the oxalate and calcium content of Kikuyu grass (Pennisetum clandestinumHochst)

The effect of the nitrogen content of Kikuyu grass on the oxalate and calcium content of leaf and stem material was investigated. The bio-availability of calcium in the herbage tended to decrease with an increase in nitrogen content of the grass. Illustrates with tables; The effect of the nitrogen content of Kikuyu grass (Pennisetum clandestinum) on the oxalate and calcium content of leaf and stem material was investigated. The grass contained equal portions of soluble and insoluble oxalate. Leaf material contained more than three times as much total oxalate as stem tissue. A high nitrogen content was associated with a high insoluble oxalate content of the sward. The calcium content of both leaf and stem material was extremely low. Results suggested that approximately 95% of the calcium could be bound as calcium oxalate and would probably not be available to ruminants. The bio-availability of calcium in the herbage tended to decrease with an increase in nitrogen content of the grass.Language: English Keywords: Analytical methods; Animal performance; Calcium; Calcium bio-availibity; Grass samples; Nitrogen; Oxalate; Rumen metabolism; calcium availability; herbage; kikuyu; leaves; pennisetum clandestinum; calcium content; kikuyu grass; grasses; ruminants; cedara research station; south africa